Magnetic system



Dec. 31, 1957 ARTHUR w. LO

MAGNETIC SYSTEM INPUT SECOND 6* OURCE W28 Filed July 27, 1955 RESETPULSE sol/R05 FIRST INPUT PUL s5 sou/m: 14

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A TTORNf Y United States Patent MAGNETIC SYSTEM Arthur W. Lo, Elizabeth,N. 1., 'assignor to Radio Corporation of America, a corporation ofDelaware Application July 27, 1955, Serial No. 524,669

'9 Claims. (CL 340-174) This invention relates to 'a magnetic system,and particularly to a system useful in controlling or switching electricsignals.

An object of the present'invention is toprovide an improved magneticsystem th'at is adapted to perform a logical-operation'in an improvedmanner.

Another object of the presentinvention is to provide an 'improvedandinexpensive magnetic system for switching magnetic signals.

Still another-object of the present invention is to provide an improvedmagnetic circuit that operates to furnish an output signal only wheneach one of a plurality of inputs is activated.

The above and [further objects of the present invention are carried outby providing a magnetic material having a rectangular hysteresischaracteristic and having a plur-ality of apertures and windingssoa-rrangedthat an output signal is induced inanv output winding woundthrough two of these apertures only if aninput signal has been appliedto both first and second input windings respectively wound th-rou-ghthesetwo apertures. Theinput signals may be applied simultaneously orsuccessively in any order.

The features oftheinvention, as well as the invention itself, both as to,itsorganizationand methodof operation, will :best be understoodfromthefollowing description, when read .in connection with theaccompanying drawing wherein:

'Fig. l is a schematic diagram of a magnetic system according to theinvention employing a core of magnetic material having a pair of settingapertures and a reset a er u Fig. 2 is a cross-sectional view of thetransfluxor .of Fig. 1 along. the line 2-2; and

Figs. 3a-3d are diagrams useful in explaining the operation of thesystem of Fig. 1. i

The magnetic system of .Fig. 1 has a multi-apertured magnetic devicemade from a magnetic material having a substantially rectangularhysteresis loop. The material is in the form of an annular core inWhich'the central aperture12 is t-ermedherein a reset aperture. The

core 10 is preferably of uniform thickness. First and second apertures,termed herein the setting apertures 14 and 16, respectively, aresymmetrically "located in the material with respect to theaper-ture 12and have their respective centers located along a horizontal (as viewedin Fig. l) center-line of the core 10, which is the section line 2- 2.The diameter of the reset aperture 12 is made larger than that of eachof the setting apertures 14 and '16, respectively, for reasonsdescribedhereinafter. The

diameter of the first and second setting apertures 14 and 16 maybeequal.

Between the periphery of the core 10 and the -apertures 14, 12, '16 arelegs '1, 2, 3, and 4, respectively The cross-sectional areasof the-legs1 through 4 taken through thernost restricted portionof the material,conveniently alongthe center line 2-.-2, are equal. Thelegs :1 and4include the material vbetween the peripherycf magnesium ferrite.

the core 10 and the inside walls of the apertures 14- and 16,respectively. The legs 2 and 3 include the material between the insidesurface of the reset aperture 12 and the inside surface of the settingapertures 14 and 16, respectively.

A cross-sectional view of the core 10 taken along the center-line 2-2 isshown in Fig. 2. The thickness 2 of the device 10 may be uniformthroughout. A suitable magnetic material may be, for example, manganese-Although the hysteresis loop may not be truly or completely rectangular,it is 'sufiiciently so forpractical purposes.

A reset winding 18 is wound through the reset aperture 12 bythreadingthe reset winding'18, beginning with the terminal 18a, acrossthe top surface of the core 10, then downwardly through the resetaperture 12, and then along the bottom surface of the core 10 to theterminal 18b. The terminals 18a and 18b of the reset winding 18 vareconnected to a reset pulse source 20. First and second setting windings22 and 24 are wound through the first and second setting apertures 14and 16, respectively, in;a manner similar to the reset winding 18beginning withthe terminals 22aand24a, respectively. The terminals 22aand 22b of the first setting winding 22 are connected to a first inputpulse source 26; and the terminals 24a and 24b of the second settingwinding 24 are connected to a second input pulse source 28.

An output winding 30 is wound through the first and second settingapertures 14 and 16. Beginning with one terminal 30a, the output winding30 is passed across the top surfaceof the core 10, then threadeddownwardly through the first-setting aperture 14, then across the bottomsurface and upwardly through the reset aperture 12, then acrossthe topsurface and downwardly through the second setting aperture 16, thenacross the bottom surface, then aroundthe edgeand across the top surfaceof the core 10 to the ,t erminal 30b. The output winding terminals 30,and 30b areconnected to a utilization device 32. Th efvariouswindingsare shown herein as singleturn windings for simplicityof drawing. Whendesired multi-turn windings may be employed.

Each of the sources herein is preferably a constant current sourcesuchas a pentodetype vacuum tube circuit. The sources are arranged tofurnish a pulse of one-polarity, for example, positive, to therespective windin'gs. The respective directions of current flow(conventional) in windings 1'8, "2'2 and 24is indicated by the arrowsadjacent thereto.

The operation "of the system of Fig. 1 maybe explained in connectionwith the diagrams'of Figs. 3a to 3d. There is an individual flux pathabout each of the apertures. *In addition to the individual flux ipaths,there exist three other longer flux paths which are presently ofinterest; two. of these-longer paths .13 and 15 are respectively aboutthe resetaperture-IZ and the first setting aperture 14 and about thereset aperture 12 and the second setting aperture 16. {The third longerpath (not shown) is about all three of the apertures.

For purposes of yexplanation of the operation of the system of Fig. 1, aparticular one of the two possible states of saturation of a magneticmaterial produced by a current pulse is arbitrarily assumed tocorrespond to one sense of-tlux orientation along a closed flux path.Briefly, there are two senses of flux flow around a closed path.positive (conventional) current flow intersectingly through a surfacebounded by the path produces a clockwise (as viewed from that side ofthe surface toward and through which the current flows) flux around thepath linked bythe current. This rule corresponds to the so-called"right-hand rule. One state of saturation, with .reference to aclosedpath, is that in which the saturating 3 other state of saturation,with reference to that path, is that in which the saturating flux isoriented in the opposite sense around the closed path.

One manner of operating the system of Fig. 1 is as follows: Assume thatthe reset pulse source 20 is operated to apply a positive reset pulse 34to the reset winding 18. The amplitude of the reset pulse is madesufiicient to estabiish a clockwise saturating flux in each of the legs1-4 around the reset aperture 12. The flux orientation in the respectivelegs, upon the termination of the reset pulse 34, is shown by the solidarrows of the diagram of Fig. 3a. Initially, the output winding 30 maybe open-circuited so that any voltage induced therein by the reset pulsedoes not produce any current fiow.

Assume, now, that the first input pulse source 26 is operated to apply apositive setting pulse 36 to the first setting winding 22. This settingpulse produces a flux change in the legs 1 and 3 from the clockwise tothe counter-clockwise sense around the first setting aperture No fluxchange is produced in the leg 2 because, in the reset condition, the leg2 is already saturated with flux oriented in the counter-clockwise sensearound the first setting aperture 14. The flux orientation, upon thetermination of the setting pulse 36, is indicated by the arrows in therespective legs of the diagram of Fig. 3b. The dotted arrows indicatethe changed flux caused by the setting pulse. No output voltage isinduced in the output winding 30 by the first setting pulse 36 becausethe output winding 30 does not link either of the legs 1 and 3.

The amplitude of the setting pulse is made greater than a certainminimum value to achieve a complete flux reversal in all portions of thelegs 1 and 3. This minimum amplitude depends upon the coercive force ofthe magnetic material employed and the radial distance of the outerportion of the leg 3 from the first setting aperture 14. For a core ofgiven thickness and uniform coercive force, the minimum amplitude isessentially proportional to the radial distance of the leg 3 from thefirst setting aperture 14. The setting pulse, however, may be of anindefinitely large amplitude without producing any flux change in theleg 4. No flux change is produced in the leg 4 because all the fiuxchange of the leg 1 will be absorbed by the equal leg 3 before any fluxchange is produced in the leg 4. A new reset pulse 34 can be applied tothe reset windmg 13 to return the core 10 back to the reset condition.The flux in the respective legs 14 is again oriented in a clockwisesense around the reset aperture 12. The new reset pulse does not induceany voltage across the terminals of the output winding 30 because thelegs 1 and 3 are not linked by the output winding 30.

Assume. now. that the second input pulse source 28 is o erated to applya positive setting pulse to the second i setting winding 24. Thispositive setting pulse produces flux change in the legs 2 and 4 from theclockwise to the counterclockwise sense with reference to (that is,

a ound) the second setting aperture 16. No flux change is p duced in theleg 3 because the leg 3 is already saturated with flux in thecounter-clockwise sense with referto the second setting aperture 16. Noflux change is produced in the distant leg 1. because all the fluxchange in the leg 4 is absorbed by the near leg 3 before any flux changeis produced in the distant leg 1. No net output voltage is induced inthe output winding 30 because the output winding 30 links the legs 2 and4 in opposite senses and the individual voltages resulting from the fluxchanges in these legs cancel each other. Following the application ofthe second setting pulse 38, another reset pulse 34 can be applied tothe reset winding 18, thereby returning the transfluxor 10 to a resetcondition. The reset pulse still does not induce any voltage across theterminals of the output winding 30 because the legs 2 and 4 are linkedin opposite senses by the output winding 30. For example, the fluxchange in the leg'4 tends to make the terminal 30:: of the outputwinding positive, and the flux change in the leg 2 tends to make theterminal. 30:: negative. The induced voltages resulting from theseseparate flux changes are of opposite polarity, of substantially equalamplitude and cancel each other.

Assume, now, that the first input pulse source 26 is operated and thenthe second input pulse source 28 is operated. The flux orientation afterthe operation of the first input pulse source 26 is indicated in Fig. 3bby the arrows in the respective legs. Note that the flux in both thelegs 3 and 4 is oriented in the clockwise sense with reference to thesecond setting aperture 16. Accordingly, when the second input pulsesource 28 is operated, a flux change from the clockwise to thecounter-clockwise direction is produced in the legs 3 and 4. No fluxchange is produced in the now distant leg 2 because the leg 3 absorbsall the-flux change produced in the leg 4. .The flux change produced inthe leg 4 alone induces a voltage across the terminals of the outputwinding 30 which is applied to the utilization device 32.

A subsequent reset pulse returns the flux in the legs 1 and 4 back tothe initial clockwise sense, with reference to the reset aperture 12. Anoutput voltage is now induced across the terminals of the output winding30 by the reset pulse. The latter output voltage is of an oppositepolarity to that produced when the second setting pulse is applied tothe second setting winding 24. If desired, the output voltage producedby the reset pulse can be prevented from causing a current flow byconnecting, for example, a suitably poled unilateral conducting device(not shown) in series with the output winding 30.

Similarly, an output voltage is induced across the terminals of theoutput winding 30, when the first input pulse source 26 is operatedsubsequent to the operation of the second input pulse source 28. Forexample, assume that the system is reset. Activation of the second inputpulse source 28 produces a flux change along the path 15. The changedflux in the legs 4 and 2 is indicated by the dotted arrows of Fig. 3c inthese legs. Note that the flux in the legs 1 and 2 about the firstsetting aperture 14 is now oriented in the clockwise sense, withreference to the first setting aperture 14. Thus, a subsequent settingpulse from the first input pulse source 26 reversesthe flux around thefirst setting aperture 14 from the clockwise to the counter-clockwisesense. The flux change in the leg 2 induces a voltage across theterminals of the output winding 30; and a signal is applied to theutilization device 32. No flux change is produced in the distant leg 3because the leg 2 now absorbs all the flux change of thelegl.

A following reset pulse again changes the flux in the legs 1 and 4 backto the clockwise sense with reference to the reset aperture 12. Again,the flux change in the leg 4 induces a voltage across the terminals ofthe output winding 30 when the reset pulse is applied.

An output voltage is also obtained when the two setting pulses areapplied simultaneously. In such case, there is a flux change in the legs1 and 4 around the longer path about all three apertures. The fluxorientation in the leg 3 is held in the counterclockwise sense, withreference to the second setting aperture 16, due to the magnetomotiveforce generated in this direction by the second setting pulse.Similarly, the flux in the leg 2 is held in the counter-clockwise sense,with reference to the first setting aperture 14, by the magnetomotiveforce in this direction generated by the first setting pulse. Therefore,only the flux in the legs 1 and 4 change. The output voltage resultsfrom the fiux change in the leg 4.

The output voltage and current depend somewhatupon the impedance of theutilization device 32. If the impedance of the utilization device isrelatively low, a relatively large current flows in the output winding30 when rent is in a direction to hold the leg -'3 saturated in theclockwise sensewith reference to the second setting aperture 16.Accordingly, some flux change is .produced in the second longer path 15about the second setting aperture 16 and the blocking aperture 12,thereby bypassing some of the flux change-produced in the leg 4 to thedistant leg 2. The flux change along the second longer path 15 does notadd to the outputsignal and, therefore, the output signal is reduced bya corresponding amount. If the utilization device has a-high impedance,most of the flux change is produced in the path about only the secondsetting aperture 16 including the legs 3 and 4. The flux loss is reducedsomewhat by making the diameter of the blocking aperture 12 larger thanthat of the setting apertures 14 and 16. In many applications, the fluxloss resulting from the flux change about the longer path 15 isunimportant, vfor example, ,when the device ,10 is operated as a digitaldevice.

Instead of returning the output winding 30 across the top surface of thecore to the terminal 30b, the output winding can be returned along thebottom surface of the core .to .the terminal 30b. In this case the legs1 and 3 are-linked bythe output winding. The roles of the legs 1 and 3,and 2 and 4 are interchanged. Otherwise, the operation of the device '10is the same and no output signal 'isapplied to the utilization device32unless both the first and the secondinput pulse sources have beenoperated.

There has been described herein an improved magnetic system forswitching electric signals by means of a multiapertured magnetic core.The system of the present in vention operates as a logical and gatecircuit. That is, no output signal is produced unless both inputs havebeen activated. The inputs may be activated simultaneously orsequentially in any desired order. Other shapes than the annular coredescribed may be employed so long as the relationship between therespective legs and the manner of linking the output winding ispreserved.

What is claimed is:

l. A magnetic device comprising a body of magnetic material having twostable remanent states, said body having first, second and thirdapertures and a plurality of legs therein, a first and a second of saidlegs respectively being defined by the material between the outside edgeof said body and the inside surface of said first and second apertures,and a third and fourth of said legs respectively being defined by thematerial between the inside surface of said third aperture and theinside surface of said first and second apertures, a first winding meanswound through said third aperture for establishing flux in one sense inall of said legs with respect to said third aperture, separate secondand third winding means respectively wound through said first and secondapertures, and a fourth winding means linking one of said first andsecond legs and one of said third and fourth legs, whereby a signal isinduced in said fourth winding means only when said second and saidthird winding means have received excitations.

2. A magnetic device comprising an annularly shaped core of magneticmaterial having two stable remanent states, said core having a centralaperture, said core having at least two other apertures each through aportion of the material between the inner and outer radial dimensionsthereof, first and second windings respectively wound through separateones of said other apertures, and another winding wound through saidother apertures and linking a portion of the material adjacent each ofsaid other apertures, said other winding serving as an output for thedevice, whereby an output signal is produced only when said first andsecond windings have received signals.

3. A magnetic device comprising a body of magnetic material having twostable remanent states, said body having first, second and thirdapertures and a plurality of legs therein, a first and a second of saidlegs respectively being defined by the material between the outside edgeof said body and the inside surface of said first and second apertures,and a third and fourth of said legs respectively being defined by thematerial between the inside surface of said third aperture and theinside surface of said first and second apertures, said first and secondapertures being so located in said body that the crosssectional areas atthe most restricted portion of the first and second of said legs aresubstantially equal to each other, a first winding means wound throughsaid third aperture for establishing a fiux in one sense in all of saidlegs with respect to said third aperture, separate second and thirdwinding means respectively wound through said first and secondapertures, and a fourth winding means wound through both said first andsecond apertures, whereby a signal is induced in said fourth windingmeans only when said second and third winding means have receivedexcitations.

4. A magnetic device comprising a body of magnetic material having twostable remanent states, said body having first, second and thirdapertures and a plurality of legs therein, a first and a second of saidlegs respectively being defined by the material between the outside edgeof. said body and the inside surface of said first and second apertures,and a third and fourth of said legs respectively being defined by thematerial between .the inside surface of said third aperture and theinside surface of said first and second apertures, said apertures beingso located in said body that the cross-sectional area at the mostrestricted portions of said third and second legs is at least equal tothe cross-sectional area at the most restricted portions of said firstand fourth legs, respectively, a first winding means wound through saidthird aperture for establishing a flux in one sense in all of said legswith respect to said third aperture, separate second and third windingmeans respectively wound through said first and second apertures, andfourth winding means linking only two of said legs, whereby a signal isinduced in said fourth winding means only when said second and saidthird winding means have received excitations.

5. A magnetic device comprising an annularly shaped core of magneticmaterial having two stable remanent states, said core having a centralaperture, said core having at least two other apertures each through aportion thereof between the inner and outer radial dimensions thereof,the inner radial dimension of said core being substantially greater thanthe dimensions of any one of said other apertures, separate first andsecond windings wound respectively through a first and a second of saidother apertures, a third winding wound through said first and secondapertures exclusively, said third winding serving as an output windingfor the device in which an output signal is produced only when saidfirst and second windings have received signals.

6. A magnetic device comprising a body of magnetic material having twostable remanent states, said body having first, second and thirdapertures and a plurality of legs therein, a first and a second of saidlegs respectively being defined by the material between the outside edgeof said body and the inside surface of said first and second apertures,and a third and fourth of said legs respectively being defined by thematerial between the inside surface of said third aperture and theinside surface of said first and second apertures, a first winding meanswound through said third aperture for establishing a flux in one sensein all of said legs with respect to said third aperture, second andthird winding means respectively wound through said first and secondapertures, and a fourth winding means wound through said first andsecond apertures so as to link only said second and third legs, wherebya signal is induced in said fourth winding means only when said secondand said third winding means have received excitations.

7. A magnetic device comprising a body of magnetic material having twostable remanent states, said body having first, second and thirdapertures and a plurality of legs therein, a first and a second of saidlegs respectively being defined by the material between the outside edgeof said body and the inside surface of said first and second apertures,and a third and fourth of said legs respec' tively being defined by thematerial between the inside surface of said third aperture and theinside surface of said first and second apertures, a first winding meanswound through said third aperture for establishing a fiua in one sensein all of said legs with respect to said third aperture, second andthird winding means respectively wound through said first and secondapertures, and a fourth winding means wound through said first andsecond apertures 80 as to link only said second and third legs, wherebya signal is induced in said fourth winding means only when said secondand said third winding means have received excitations.

8. A magnetic device comprising a unitary core consisting of magneticmaterial characterized by having a substantially rectangular hysteresisloops, said core having a central aperture and at least two otherapertures each through a portion thereof between the inner and outerradial dimensions thereof, separate first and second windingsrespectively wound through first and second ones of said otherapertures, and a third Winding wound through said first and secondapertures exclusively, said third 8 winding, serving as an outputwinding for the device in which an output signal is produced only whensaid first and second windings have received signals.

9. Arnagnetic device comprising a unitary core consisting of magneticmaterial characterized by having a substantially rectangular hysteresisloop, said core having a central aperture and at least two otherapertures each through a portion thereof between the inner and outerradial dimensions thereof, separate first and second windingsrespectively wound through first and second ones of said otherapertures, and a third winding having first and second terminals, saidthird winding being wound so as to link only the material between saidcentral and first apertures and the material between said secondaperture and the periphery of said core, said third winding serving asan output winding for the device in which an output signal is producedonly when said first and second windings have received signals.

References Cited in the file of this patent UNITED STATES PATENTS2,284,406 DEntrernont May 26, 1942 2,519,425 Barlow Aug. 22, 19502,519,426 Grant Aug. 22, 1950 2,614,167 Kamm Oct. 14,1952 2,640,164 Gielet al. May 29, 1953 2,708,219 Carver May 10, 1955 of the above numberedpatent requiring c U. Sr DEPARTMENT OF COMMERCE PATENT OFFICECERTIFICATE OF CORRECTION Patent No 2,818,556 Arthur W. Lo December 31,1957 It is hereby certified that error appears.in the printedspecification orrection and that the said Letters Patent should read ascorrected below.

Column 7, line 1, beginning with "7. A magnetic" strike out all to andincluding "excitations," in line 19, same column; line 20, for the claimnumber "8," read --ZP; line 22, for "loops" read --loop--; column 8,line 4, for the claim number "9." read -8.---

in the heading to the printed specification, line 6, for "9 Claims" read--8 Claims--o Signed and sealed this let (1a; of July 1958,

(SE Attes KARL H. AXLINE ROBERT C. WATSON Attestlng Officer Commissionerof Patents U. 8.. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OFCORRECTION Patent No, 2,818,556 Arthur W. Lo December 31, 1957 It ishereby certified that error appears .in the printed specification of theabove numbered patent requiring correction and that the said LettersPatent should read as corrected below.

Column "7, line 1, beginning with "'70 .A magnetic" strike out all toand including "excitations." in line 19, same column; line 20, for theclaim number "80'! read ---'7d-=-;' line 22, for "loops" read .--loop--;column 8, line 4, for the claim number "9." read 80-; in the heading tothe printed specification, line 6, for "9' Claims" read --8 Claims-Signed and sealed this 1st as; of July 1958.,

Q (SE Attes KARL H. AXLINE ROBERT C. WATSON Attesting OfficerComnissioner of Patents

